pH对氢基质自养微生物还原降解对氯硝基苯的影响

Effect of pH on reductive degradation of para-chloronitrobenzene by autohydrogenotrophic microorganisms

在建立的一种MBfR（氢基质生物膜反应器）中系统考察pH对氢基质自养微生物还原降解p-CNB（对氯硝基苯）的影响,并重点分析pH影响下p-CNB、p-CAN（对氯苯胺）、NO-3-N（硝酸盐）和SO2-4（硫酸盐）的去除效率、通量及当量电子转移通量的变化趋势.结果表明,pH在5.7~8.7之间变化时对硝基还原、还原脱氯、反硝化和硫酸盐还原过程影响显著.氢基质自养微生物生长较适宜的pH范围为6.7~8.2,其中硝基还原、还原脱氯、反硝化和硫酸盐还原的最佳pH分别是7.7、8.2、7.2和7.2.当量电子转移通量分析表明,反硝化和硫酸盐还原对pH变化的敏感性均强于p-CNB还原.为了维持较高水平的p-CNB、NO-3-N和SO2-4同步去除效率,可将pH调控在7.2~8.2之间.适当地调节pH有利于微生物的生长以及控制中空纤维膜表面矿物质沉淀引起的膜污染.

Effect of pH on reductive degradation of p-CNB （para-chloronitrobenzene） by autohydrogenotrophic microorganisms in a MBfR （hydrogen- based membrane biofilm reactor） was systemically investigated, and the removal efficiencies, water fluxes and electron-equivalent fluxes of p-CNB, p- CAN （para-chloraniline）, NO3-N （nitrate） and SO4-（sulfate） under the influence of pH were analyzed. The experimental results show that, when pl-I varied from 5.7 to 8.7, nitro reduction, reductive dechlorination, denitrification and sulfate reduction were significantly affected by pH. An appropriate pH for the growth of autohydrogenotrophic microorganisms ranged from 6.7 to 8.2, and the optimum pH of nitro reduction, reductive dechlorination, denitrification and sulfatereduetion were 7.7,8.2,7.2 and 7.2, respectively. Analysis of electron-equivalent fluxes reveals both denitrification and sulfatereduction were more sensitive to pH variation than p-CNB reduction. In order to maintain a high level of simultaneous removal efficiencies of p-CNB, NO4-N and SO4-, pH can be maintained to 7.2~8.2. Appropriate adjustment of pI-I is conducive to microbial growth and control membrane fouling for precipitation of minerals on surface of the hollow fiber membranes.